All life on Earth, and indeed all matter in the universe, is ultimately composed of atoms. The most abundant element in the universe is hydrogen, which makes up roughly 75% of all baryonic matter. Even heavier elements like carbon, nitrogen, and oxygen are ultimately formed from hydrogen through processes like nuclear fusion in stars. So, in a sense, all life is nothing but hydrogen given time. The atoms that make up our bodies, the food we eat, and the air we breathe were all formed from hydrogen in the early universe or through the nuclear reactions in stars. In a way, we are all made of stardust, and our ultimate origin can be traced back to the hydrogen that permeates the cosmos.